Re: [PATCH v8 5/5] pwm: dwc: add of/platform support

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

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On Wed, Jun 14, 2023 at 06:14:57PM +0100, Ben Dooks wrote:
> The dwc pwm controller can be used in non-PCI systems, so allow
> either platform or OF based probing.

A document describing the binding is needed here.

> 
> Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
> ---
> v8:
>  - add compile test for of-case
>  - add module namespace
>  - move later in the series
> v7:
>  - fixup kconfig from previous pcie changes
> v5:
>  - fix missing " in kconfig
>  - remove .remove method, devm already sorts this.
>  - merge pwm-number code
>  - split the of code out of the core
>  - get bus clock
> v4:
>  - moved the compile test code earlier
>  - fixed review comments
>  - used NS_PER_SEC
>  - use devm_clk_get_enabled
>  - ensure we get the bus clock
> v3:
>  - changed compatible name
> ---
>  drivers/pwm/Kconfig        | 10 +++++
>  drivers/pwm/Makefile       |  1 +
>  drivers/pwm/pwm-dwc-core.c |  6 +++
>  drivers/pwm/pwm-dwc-of.c   | 78 ++++++++++++++++++++++++++++++++++++++
>  drivers/pwm/pwm-dwc.c      |  1 +
>  drivers/pwm/pwm-dwc.h      |  1 +
>  6 files changed, 97 insertions(+)
>  create mode 100644 drivers/pwm/pwm-dwc-of.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 7c54cdcb97a0..61f5d3f30fd7 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -205,6 +205,16 @@ config PWM_DWC
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-dwc.
>  
> +config PWM_DWC_OF
> +	tristate "DesignWare PWM Controller (OF bus)"
> +	depends on HAS_IOMEM && (OF || COMPILE_TEST)
> +	select PWM_DWC_CORE
> +	help
> +	  PWM driver for Synopsys DWC PWM Controller on an OF bus.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-dwc-of.
> +
>  config PWM_EP93XX
>  	tristate "Cirrus Logic EP93xx PWM support"
>  	depends on ARCH_EP93XX || COMPILE_TEST
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index de3ed77e8d7c..d27dfbb850b7 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_PWM_CRC)		+= pwm-crc.o
>  obj-$(CONFIG_PWM_CROS_EC)	+= pwm-cros-ec.o
>  obj-$(CONFIG_PWM_DWC_CORE)	+= pwm-dwc-core.o
>  obj-$(CONFIG_PWM_DWC)		+= pwm-dwc.o
> +obj-$(CONFIG_PWM_DWC_OF)	+= pwm-dwc-of.o
>  obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
>  obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
>  obj-$(CONFIG_PWM_HIBVT)		+= pwm-hibvt.o
> diff --git a/drivers/pwm/pwm-dwc-core.c b/drivers/pwm/pwm-dwc-core.c
> index 0f07e26e6c30..ed102fc4b30a 100644
> --- a/drivers/pwm/pwm-dwc-core.c
> +++ b/drivers/pwm/pwm-dwc-core.c
> @@ -16,6 +16,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
> +#include <linux/clk.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pwm.h>
>  
> @@ -44,6 +45,9 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
>  	u32 high;
>  	u32 low;
>  
> +	if (dwc->clk)
> +		dwc->clk_rate = clk_get_rate(dwc->clk);
> +
>  	/*
>  	 * Calculate width of low and high period in terms of input clock
>  	 * periods and check are the result within HW limits between 1 and
> @@ -128,6 +132,8 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  
>  	pm_runtime_get_sync(chip->dev);
>  
> +	if (dwc->clk)
> +		dwc->clk_rate = clk_get_rate(dwc->clk);
>  	clk_rate = dwc->clk_rate;
>  
>  	ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm));
> diff --git a/drivers/pwm/pwm-dwc-of.c b/drivers/pwm/pwm-dwc-of.c
> new file mode 100644
> index 000000000000..13a0b534b383
> --- /dev/null
> +++ b/drivers/pwm/pwm-dwc-of.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * DesignWare PWM Controller driver OF
> + *
> + * Copyright (C) 2022 SiFive, Inc.
> + */
> +
> +#define DEFAULT_MODULE_NAMESACE dwc_pwm

missing P? I'd have put this into drivers/pwm/pwm-dwc.h.

> +
> +#include <linux/bitops.h>
> +#include <linux/export.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/clk.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/pwm.h>
> +#include <linux/io.h>
> +
> +#include "pwm-dwc.h"
> +
> +static int dwc_pwm_plat_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct dwc_pwm *dwc;
> +	struct clk *bus;
> +	u32 nr_pwm;
> +
> +	dwc = dwc_pwm_alloc(dev);
> +	if (!dwc)
> +		return -ENOMEM;
> +
> +	if (!device_property_read_u32(dev, "snps,pwm-number", &nr_pwm)) {
> +		if (nr_pwm > DWC_TIMERS_TOTAL)
> +			dev_err(dev, "too many PWMs (%d) specified, capping at %d\n",
> +				nr_pwm, dwc->chip.npwm);
> +		else
> +			dwc->chip.npwm = nr_pwm;
> +	}
> +
> +	dwc->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(dwc->base))
> +		return PTR_ERR(dwc->base);
> +
> +	bus = devm_clk_get_enabled(dev, NULL);
> +	if (IS_ERR(bus))
> +		return dev_err_probe(dev, PTR_ERR(bus),
> +				     "failed to get clock\n");
> +
> +	dwc->clk = devm_clk_get_enabled(dev, "timer");
> +	if (IS_ERR(dwc->clk))
> +		return dev_err_probe(dev, PTR_ERR(dwc->clk),
> +				     "failed to get timer clock\n");
> +
> +	dwc->clk_rate = clk_get_rate(dwc->clk);

Do you need this here? Isn't clk_rate assigned each time it's used when
clk != NULL?

> +	return devm_pwmchip_add(dev, &dwc->chip);
> +}
> +
> +static const struct of_device_id dwc_pwm_dt_ids[] = {
> +	{ .compatible = "snps,dw-apb-timers-pwm2" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, dwc_pwm_dt_ids);
> +
> +static struct platform_driver dwc_pwm_plat_driver = {
> +	.driver = {
> +		.name		= "dwc-pwm",
> +		.of_match_table  = dwc_pwm_dt_ids,
> +	},
> +	.probe	= dwc_pwm_plat_probe,
> +};
> +
> +module_platform_driver(dwc_pwm_plat_driver);
> +
> +MODULE_ALIAS("platform:dwc-pwm-of");
> +MODULE_AUTHOR("Ben Dooks <ben.dooks@sifive.com>");

Given that this email address is (or soon will be) unavailable, maybe
better put your codethink address here?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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